Outer suspension type lens shielding mask for projection apparatus

ABSTRACT

An outer suspension type lens shielding mask for a projection apparatus including a sheet body and holding element, in which a rectangular hole is opened in the sheet body, and the sheet body is combined with the holding element to be fixed on a projection apparatus. Another outer suspension type lens shielding mask includes a base plate, in which a rectangular hole is opened in the middle part thereof, and upper and lower adjustable plates are installed behind the base plate. An open rectangular notch is respectively disposed at the middle parts of the upper and the lower adjustable plates. An adjustment mechanism includes a plurality of connecting elements connected to the base plate and the upper and the lower adjustable plates for adjusting the relative positions thereof, to avoid bad shadows yielded outside of a picture due to light diffraction and improve the quality of visual amusement.

This application is a Divisional of co-pending application Ser. No.10/952,836, filed on Sep. 30, 2004, and for which priority is claimedunder 35 U.S.C. § 120; and this application claims priority ofapplication Ser. No. 093114660 filed in Taiwan, R.O.C. on May 24, 2004under 35 U.S.C. § 119; the entire contents of all are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an outer suspension type lens shieldingmask for a projection apparatus, and more particularly to a lensshielding mask mounted outside of a projection lens and designed formatching all kinds of aspect ratios of projection pictures to reduce theleaking of the diffusion light outside of the picture.

2. Description of Related Art

Diffusion light is yielded in a general projector when light isexperienced a several reflection and projection after it is emitted froman optical engine. And, a contrast is lowered after the diffusion lightis leaked out through the projection lens so that the quality of a darkscene is influenced when the projector is used on such as a home videopicture playing.

Therefore, for lowering the darkness of the dark scenes of a motionpicture in a projector to enhance the performance of contrast, anoptical grating is always added in an optical engine system. But, notonly needs it to add elements in entire optical engine or change adesign but also helps it nothing for a currently existed projector modelif the optical grating is added in the optical engine. Therefore,substantially, it is necessary to add an optical grating device withoutchanging the internal structure of a current projector and increasingproduction cost.

SUMMARY OF THE INVENTION

The main object of the present invention is to provide an outersuspension type lens shielding mask for a projection apparatus, capableof being mounted outside of a projection lens and being designed to astatic optical grating or adjustable optical grating matching with everykind of different aspect ratio of projection picture.

Another object of the present invention is to provide an outersuspension type lens shielding mask for a projection apparatus, capableof reducing production cost by elevating the picture quality from theoutside of the projection apparatus without changing the design of anoptical engine.

Still another object of the present invention is to provide an outersuspension type lens shielding mask for a projection apparatus, capableof avoiding bad shadow outside of a picture caused from diffractionlight so as to improve the quality of sight amusement.

For attaining to the objects mentioned above, an outer suspension typelens shielding mask for a projection apparatus according to the presentinvention comprises a sheet body and a holding element, in which arectangular hole is opened in the sheet body and the sheet body iscombined with the holding element together for being fixed on aprojection apparatus. Another outer suspension type lens shielding maskaccording to the present invention comprises a base plate, in which arectangular hole is opened in the middle part thereof, upper and loweradjustable plates, installed behind the base plate and an openrectangular notch is respectively disposed at the middle parts of theupper and the lower adjustable plates, and an adjustment mechanism,consisting a plurality of connecting elements connected to the baseplate and the upper and the lower adjustable plates for adjusting therelative positions of the upper and the lower adjustable plates on thebase plate.

Further scope of the applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawings,which are given by way of illustration only, and thus are not limitativeof the present invention, and in which:

FIG. 1 is a prospective view, showing a lens shielding mask with a fixedtype optical grating of a preferred embodiment according to the presentinvention;

FIGS. 2A and 2B are schematic views, showing a motion for mounting alens shielding mask with a fixed type optical grating onto a projectionapparatus;

FIG. 3 is an explosive view, showing a lens shielding mask with anadjustable optical grating of another preferred embodiment according tothe present invention;

FIG. 4 is a cross sectional view, showing an assembled lens shieldingmask with an adjustable optical grating of another embodiment accordingto the present invention;

FIG. 5 is a schematic view, showing a motion for mounting a lensshielding mask with a fixed type optical grating onto a projectionapparatus;

FIG. 6 is an explosive view, showing a lens shielding mask with anadjustable optical grating of still another preferred embodimentaccording to the present invention; and

FIG. 7 is a cross sectional view, showing an assembled lens shieldingmask with an adjustable optical grating of still another embodimentaccording to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIG. 1. FIG. 1 is a prospective view showing a lensshielding mask with a fixed type optical grating of a preferredembodiment according to the present invention. A lens shielding mask 10with a static optical grating mainly comprises a circular disc typesheet body 101 made from an opaque material or a flat plate coated withan opaque material on the surface thereof and used for shieldingdiffraction light projected from a lens of a projector; the diameterthereof is approximately equal to the inner diameter of a outer frame infront of the lens of the projector as FIGS. 2A and 2B show. Arectangular hole 102 whose shape and location depend on the type of thelens is opened in the sheet body 101. Because the aspect of a generalpicture is 16:9, although the ratio of the length and the width of therectangular hole is always fabricated to be 16:9, but it can also befabricated to be 4:3 or even 2.35:1 for accommodating it to a differentaspect ratio. The hole 102 is deviated from the center of the sheet body101 according to the present invention. A plurality of clamping ears 103are disposed around the circumference of the sheet body 101. Theseclamping ears can be formed with the sheet body 101 into one body orcombined with the sheet body 101 by means of adhesion or welding. Thenumbers and the locations of the clamping ears 103 are not particularlydefined, only that a user can mount the lens filtering mask 10conveniently on the outer frame of the lens of the projector is enough.In addition, a material such as fiber can be stuck on the circumferenceof the circular sheet body 101 for being taken as a clamping element toallow the sheet body to be engaged tightly in the outer frame of thelens.

The motion for mounting the lens filtering mask with a fixed typeoptical grating mentioned above can be seen in FIGS. 2A and 2B. A useronly uses his fingers to clip the clamping ears 103 on the sheet body101 and aims the mask at and then mounts it on the outer frame 3 outsideof the lens 2 of the projector 1. Thereafter, the fingers are again usedto clip the lens filtering mask 10 to rotate the sheet body 101 untilthe rectangular hole is aligned with a formation zone of image after thelens shielding mask 10 is mounted on the outer frame 3.

Next, please refer to FIGS. 3 and 4. FIGS. 3 and 4 are explosive andcross sectional views respectively showing parts and after-assemblystructure of a lens shielding mask with an adjustable optical grating ofanother preferred embodiment according to the present invention. A lensfiltering mask 20 with an adjustable optical grating comprises a baseplate 201 and upper and lower adjusting plates 202 and 203. A sleeve2011 is disposed at each corner of the base plate 201 and a rectangularhole 204 whose shape and location is disposed depending on the aspect ofa lens is opened in the base plate 201; according to the presentinvention, the hole is symmetrical to a center line in the direction ofthe width of the base plate (i.e. line A–A′ in FIG. 3), and the centerpoint of the hole 204 is also disposed at a location beyond the centerline in the direction of the length of the base plate (i.e. line B–B′ inFIG. 3) according to the design of the location of a picture projectedfrom a general projector. Furthermore, open type rectangular notches2022 and 2032 are respectively disposed at the centers of the lower edgeof the upper adjusting plate 202 and the upper edge of the loweradjustable plate 203, the sizes of these two open type rectangularnotches 2022 and 2032 are same and corresponding to each other. And,sleeves 2021 and 2031 are respectively disposed at both of the left andthe right sides of the rectangular notches 2022 and 2032 of the upperand the lower adjustable plates 202 and 203. The sizes of the centerholes of the sleeves 2011, 2021 and 2031 respectively disposed at theleft and the right sides of the base plate 201 and the upper and thelower adjustable plates are same; the center lines of the center holesat the left and the right sides are respectively aligned into one lineand the two lines are parallel after assembly as FIG. 4 shows. Inaddition, screws exist in the center holes of only one pair of thesleeve 2021 at the right side of the upper adjustable plate 202 and thesleeve 2031 at the left side of the lower adjustable plate 203, and thesleeve 2021 at the left side of the upper adjustable plate 202 and thesleeve 2031 at the fight side of the lower adjustable plate 203 and canbe extended out of them to screw thread portions 2023 and 2033 tostrengthen the moving stability when the upper and the lower adjustableplates driven by a bolt 205. For convenience in explanation, the formerstructure is adopted in FIGS. 3 and 4, i.e. the screw threads are onlydisposed in the center holes of the sleeve 2021 at the right side of theupper adjustable plate 202 and the sleeve 2031 at the left side of thelower adjustable plate 203. And, no screw thread exists in the centerholes of all the sleeves on the base plate 201.

Please refer to FIG. 4. When the base 201 and the upper and the loweradjustable plate 202 and 203 want to be assembled to a lens filteringmask, the upper and the lower adjustable plates 202 and 203 are firstplaced between the upper and the lower sleeves 2011 on the base plate201. Next, two bolts 205 are respectively inserted into the sleeves2011, 2021, 2031 and 2011 disposed into one straight line at the twosides of the base plate and the upper and the lower adjustable plates202 and 203. Fixing washers 207 are then engaged with end parts 2052 ofthe bolts 205 to prevent the assembling elements from falling down afterthe bolts 205 are passed through the lowermost end of the sleeve 2011.for conforming to a different aspect of projection picture, only rotatea rotating button on the bolt 205, and the left sleeve 2021 on the upperadjustable plate 202 engaged with the bolt 205 or/and right sleeve 2031on the lower adjustable 203 can then be driven to move the upper or/andlower adjustable plate/plates upwards or downward to change the size ofa close rectangular hole formed by the open type rectangular notches2022 and 2032. Generally speaking, the ratio of the length and the widthof the adjusted close rectangular hole can be an aspect ratio of ageneral projection picture such as 4:3, 16:9, 2.35:1 or anything else.

Please refer to FIG. 5. FIG. 5 is a schematic view showing a lensshielding mask is mounted on a projector according to the presentinvention. When the lens shielding mask 20 wants to be mounted on theprojector 1, holding sheets on the base plate 201 are respectivelyclamped at the upper and the lower rims of the projector close to theprojection lens 2 and the ratio of the length and the width of the closerectangular hole is adjusted according to the steps mentioned above toconform to the aspect ratio of a projection picture.

Please refer to FIGS. 6 and 7. FIGS. 6 and 7 are explosive and crosssectional views respectively showing parts and after-assembly structureof a lens shielding mask with an adjustable optical grating of stillanother preferred embodiment according to the present invention. A lensshielding mask 30 with an adjustable optical grating comprises a baseplate 301 and upper and lower adjustable plates 302 and 303. A sleeve3011 is disposed on every corner of the base plate 301; no screw threadis existed in any one of these four sleeves. A rectangular hole 304 isfurther opened in the base plate 301; the disposition location isidentical to the rectangular hole 204 in the last preferred embodimentmentioned above so that the detail thereof is omitted here. Furthermore,in the base plate 301, two guide notches 307 are disposed at the lateralcenter line of the rectangular hole 304 and adjacent to the two flanksides of the base plate. Two open type rectangular notches 3022 and3032, which are corresponding to each other and have a same size, arerespectively disposed in the middles of the lower end of the upperadjustable plate 302 and the upper end of the lower adjustable plate303; the width of the open type rectangular notches are almost equal tothe one of the rectangular hole in the base plate. And, a lever plateconnecting seat 308 is respectively disposed at each one of the twosides of the open type rectangular notches of the upper and the loweradjustable plates 302 and 303; an accepting hole 3081 is opened in eachconnecting seat 308. Both of sleeves 3021 and 3031 are respectivelydisposed at the left and the right sides of the upper and the loweradjustable plates 302 and 303. The sizes of the center holes of thesleeves at the same sides are equal, and screw threads are disposed inthe center holes of the sleeves at the same side; the threads aredisposed in the center holes of the sleeves at the left sides of theplates according to the present invention only for explaining the detaileasily.

The assembling of the lens filtering mask 30 according to the presentinvention can be seen in FIG. 7. First, a buckling pin 3091 disposed ona lever plate shown in FIG. 6 is buckled into the accepting hole 3092disposed in a corresponding and the end of the buckling pin 3091 isengaged into the guide notch 307, and then another buckling pin 3091 oneach lever plate is engaged into the accepting hole 3081 in the eachconnecting seat 308 on the upper and the lower adjustable plate 302 and303. Each connecting point after being connected including the onebetween the lever plates 309 and the one between the lever plate 309 andconnecting seat 308 is pivotally connected. Thereafter, the whole set ofafter-combination upper and lower adjustable plates 302 and 303 and thelever plate 309 are mounted between the upper and the lower sleeves 3011on the base plate 301. After the center holes of the sleeves 3011, 3021,3031 and 3011 on the left and right sides of the base plate 30 and theupper and the lower adjustable plates 302 and 303 are aligned, a boltwith both of left and right screw threads respectively disposed on theupper and the lower parts thereof and a straight shaft shown in FIG. 6are respectively inserted into the left and the right sides of sleevearrays. Fixing washers are used to engage respectively with both ends ofthe bolt 305 and the straight shaft 306 to prevent all the assemblingelements from dropping after the bolt 305 and the straight shaft 306 arepassed through the lowermost end of the sleeve 3011. the upper and thelower adjustable plates 302 and 303 can be closed and openedsynchronically to adjust the size of the close opening formed by theopen type rectangular notches 3022 and 3032 to conform to the size ofthe projection picture after the bolt with left and right screw threadsrespectively disposed on the upper and the lower parts thereof isengaged with the sleeves 3021 and 3031 in which the threads in thecenter holes of them are reverse to each other respectively disposed onthe left sides of the upper and the lower adjustable plates. Thecoordination of the lever plates 309 and guide notches 307 and thecoordination of the straight shaft 306 and the sleeves on the right sideare operated to guide the upper and the lower adjustable plates 302 and303 to move up and down smoothly.

Furthermore, the thread of the center holes of the sleeves at the leftside can also be extended to the outsides of the sleeves to increase thedriven stability of the upper and the lower adjustable plates, it is thesame situation as described in the preferred embodiment of the presentinvention mentioned above.

Besides, the holding element used in the preferred embodiment mentionedabove can also be used in this preferred embodiment for mountingconvenience. The detail for mounting the mask on a projector is alsoomitted here because it is not different from the situation mentioned inthe last preferred embodiment.

It is noted that the outer suspension type lens shielding mask for aprojection apparatus described above is the preferred embodiments of thepresent invention for the purpose of illustration only, and are notintended as a definition of the limits and scope of the inventiondisclosed. Any modifications and variations that may be apparent to aperson skilled in the art are intended to be included within the scopeof the present invention.

1. An outer suspension type lens shielding mask for a projectionapparatus, comprising: a base plate, wherein a rectangular hole isopened therein; at least one upper adjustable plate and one loweradjustable plate, installed on said base plate, and two correspondingopen type rectangular notches being respectively disposed in the middleof the lower end of said upper adjustable plate and the upper end ofsaid lower adjustable plate; and at least one adjustment apparatus,constituted by a plurality of connecting elements connected to saidplate and said upper and said lower adjustable plates for the relativepositions of said upper and said lower adjustable plates to be adjustedon said base plate, wherein said connecting elements are sleeves andsaid sleeves are respectively disposed on the corners of said base plateand the left and the right side of said upper and said lower adjustableplates to form two arrays of sleeves and said all sleeves on said twoarrays are aligned one another; and wherein screw threads existrespectively in one pair of sleeves diagonally disposed on said upperand lower adjustable plates and no screw thread exists in another pairof said sleeves diagonally disposed on said upper and said loweradjustable plates, and said adjustment apparatus is two boltsrespectively inserted in said aligned sleeves disposed on the left andthe right sides of said base plate and said upper and said loweradjustable plates.
 2. The lens shielding mask according to claim 1,wherein screw threads are respectively extended out of said one pair ofthreaded sleeves on said upper and said lower plates.